Large Cement Lines:
just one Process Fan is enough

Air-handling specialist Venti Oelde can equip plant areas of large cement processing lines with only a single, powerful centrifugal fan. When compared with using two combined centrifugal fans, the customer saves on investment, energy and space.

Rotor assembly for raw mill fan, rotor weight 30 t

As a component of large cement lines with high flow volumes, the single powerful centrifugal fan offers numerous technical and economic advantages in comparison with two parallel operating fans. In cooperation with Venti Oelde, planners and plant constructors can depend on one large fan, even if the flow volume is higher than 1,000,000 m³/h.

For several years now larger and larger cement lines are being commissioned. Kiln lines with a capacity of more than 10,000 tonnes per day are no longer a rarity. Plant components must, therefore, be correspondingly dimensioned. Typical examples of these components are raw mill and cement mill fans, kiln fans for pre-heaters or filter fans, for example for the cooler exhaust air from large filters.


Technology keeps up

Until about five years ago the great rotor mass of large centrifugal fans would have required the use of expensive slide bearings. For this reason, in the past two fans were usually used in parallel operation.

Single fan
Two fans

In the meantime, however, there are large-sized roller bearings available, thus considerably reducing the cost of the bearing units. These now make the economical operation of one large fan possible. Many years of operational experience have proved this technical solution to be effective.


Positive experience with excellent performance

Venti Oelde heavy-duty fans have been successfully utilized in the cement industry for many years all over the world: for example, raw mill fans with flow volumes up to 1,700,000 m³/h and a drive power of more than seven MW. Venti Oelde’s cement mill fans, kiln fans and filter fans can handle flow volumes of between 1,100,000 and 1,700,000 m³/h at a drive power of four, five or more MW.


A direct comparison

For instance, one raw mill fan downstream of a cyclone compared with two smaller fans makes clear the technical advantages and cost benefit:

Flow volume at the inlet, dust content, static pressure difference and inlet temperature are identical in both cases; rotation speed and shaft output with dust are, in the case of the single fan, pleasingly lower.

One Centrifugal Fan,
Type DHRV 45S-2500/K
Two Centrifugal Fans,
Type DHRV 45B-1800/K
Flow volume at inlet 1.593.950 m³/h 2 x 796.975 m³/h
Dust content 97.549 kg/h 97.549 kg/h
Static pressure difference 12.200 Pa 12.200 Pa
Density at inlet 0,903 kg/m³ 0,903 kg/m³
Inlet temperature 89 °C 89 °C
Speed 750 rpm 993 rpm
Shaft output with dust 6.882 kW 7.278 kW (2 x 3.639 kW)

   

One Centrifugal Fan, Type DHRV 45S-2500/K
Two Centrifugal Fans, Type DHRV 45B-1800/K

Enormous saving potential

In a direct comparison the example shows an energy saving of 396 kW, or of more than five percent. Calculated on an annual basis the saving is 3,300 MW. Based on an energy price of 8 Cent/kWh and 8,400 hours of operation, the saving is about Euro 260,000 every twelve months. Furthermore, the CO₂-emission is also considerably reduced, which is environmentally friendly and offers a further saving potential.

The use of only one large fan also lowers investment costs. An operator can save more than eight percent in comparison to two-fan operation.


Further advantages

Using a single large fan saves not only costs but also valuable space as well as reducing erection time. Two parallel operating machines no longer have to be synchronised. Furthermore, less measurement and control equipment and noise protection measures are required. Moreover, pressure losses caused by additional ducting and bends are avoided. Finally, the technically mature technology ensures high availability and low maintenance effort.


Venti Oelde – the air-handling expert

Venti Oelde possesses many years of experience in designing and constructing large fans. The company is well-known for its "large solutions": apart from the cement industry Venti also supplies fans to the iron and steel industry, where, for example, there are sintering and pellet plants with flow volumes up to three million m³/h in operation.

3D animation of a large double-inlet raw mill fan